Gutter Calculator
How much gutter do you need? Enter the roofline length.
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Downspouts needed—
Estimated cost—
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How this calculator works
Measure the total length of roof edge (eaves) that needs gutters. The calculator also adds one downspout for roughly every 35 feet of gutter to drain it properly.
Worked example — 120 feet of roofline:
120 linear feet of gutter and about 4 downspouts.
Downspout spacing
One downspout per 30–40 feet of gutter keeps water moving. Long runs or heavy-rain areas benefit from more.
Frequently asked questions
How many downspouts do I need?
About one per 30–40 feet of gutter run.
How do I measure for gutters?
Add up the length of every roof edge (eave) where water needs to drain.
Planning an outdoor project
Outdoor quantities vary with site shape, access, drainage, soil conditions, and local material availability. Break irregular areas into simple sections, confirm the product specification with your supplier, and check permits or utility requirements before starting work.
How to use this estimate
- Measure the project in the units shown and recheck your measurements before ordering.
- Use the waste allowance as a planning buffer, not as a substitute for a detailed material takeoff.
- Compare the result with the package yield, coverage, or weight listed by your supplier.
- Prices are user-entered estimates and may change by location, product, delivery, and season.
Accuracy and limitations
Calculapedia provides educational planning estimates. It does not inspect your site, select products, guarantee quantities, or replace a contractor, engineer, architect, building official, or supplier. Confirm the final quantity and any safety or code requirements before buying or building.